The Stratolaunch aircraft.
Stratolaunch Systems Corporation
For decades, Ukraine's Antonov An-225 has reigned supreme as the largest plane in the world.

That is, until now.

On Wednesday, Stratolaunch rolled its low-orbit-launch aircraft out of the company's hangar in the California desert for the first time.

With wings spanning 385 feet, it is the world's largest airplane by wingspan — besting the An-225's 290 feet. The aircraft is also 238 feet long and 50 feet tall.

Like the An-225, the Stratolaunch plane is powered by six high-bypass-ratio turbofan engines.

Stratolaunch, owned by Microsoft cofounder Paul Allen, intends to use the aircraft to move forward with its vision to "provide convenient, reliable, and routine access to low-Earth orbit."

Stratolaunch Systems Corporation

"This marks a historic step in our work to achieve Paul G. Allen's vision of normalizing access to low-Earth orbit," Stratolaunch Systems CEO Jean Floyd said in a statement. "We have a lot of exciting activity ahead as we enter the testing process, and we look forward to sharing our progress during the coming months."

Ahead of the rollout, Stratolaunch removed the three-story scaffolding around the plane and lowered the 500,000-pound craft onto its 28 wheels for the first time. The Stratolaunch plane is expected to undergo ground tests, engine runs, and taxi tests before making its first flight.

Stratolaunch Systems Corporation

The company plans to use the aircraft as a platform to launch rockets into orbit, which is why it has a designed maximum takeoff weight of 1.3 million pounds. Stratolaunch says the aircraft will one day be able to deliver as many as three rockets into orbit on a single mission.

According to Stratolaunch, the aircraft is on track to perform its first launch demonstration in 2019.